The judge worked with British and US forces to prosecute Taliban, Islamic State, al-Qaida and Haqqani terrorists who were captured in Afghanistan and is therefore at serious risk of being killed by the Taliban.

He must hide from a separate location from his family and is unable to speak to them on the phone.

The UK government said, however, that he does not meet the policy criteria for being brought to Britain and that his contribution to counter-terrorism work in Afghanistan was “minimal”. Nor, they said, was he a direct employee of the UK government since the court in which he sat was an Afghan institution.

A ruling of the English High Court last month backed his claim for sanctuary in the UK.

In order to obtain a visa, the judge would have to travel to a UK visa processing centre in Pakistan. If the UK government refuses him a visa, however, he would be deported to Afghanistan and into the hands of the Taliban.

Mrs Justice Lieven’s judgment states: “I do accept that if it did happen it would place JZ [anonymised initials used in the ruling] and possibly his family at real and immediate risk of death.”

The judge told The Guardian through an intermediary: “I was once considered an important ally … I am heartbroken, abandoned and feel backstabbed by the government for refusing to relocate me in the UK.”

An MoD spokesperson said: “To date we have relocated over 9,000 applicants and their dependants to the UK.”